Infantile Seizure

Infantile spasms (also called IS) are also known as West syndrome because it was first described by Dr. William James West, in the 1840s. The spasms consist of a sudden stiffening. Often the arms flung out as the knees are pulled up and the body bends forward ("jackknife seizures"). Less often, the head can be thrown back as the body and legs stiffen in a straight-out position. Movements can also be more subtle and limited to the neck or other body parts. Infants can cry during or after the seizure. Each seizure lasts only a second or two but they usually occur close together in a series. Sometimes the spasms are mistaken for colic, but the cramps of colic do not occur in a series.

Babies with Infantile spasms often seem to stop developing as expected. Or they may lose skills like sitting, rolling over, or babbling. 

Infantile spasms are most common just after waking up and rarely occur during sleep.

Who gets it?

Infantile spasms is considered an age specific epilepsy that typically begin between 3 and 8 months of age. Almost all cases begin by 1 year of age and usually stop by the age of 2 to 4 years. IS is not common - they affect only one baby out of a few thousand. About 2/3 of babies with IS have some known cause for the seizures. A number of conditions may cause changes in the way the brain forms or functions. For example problems with a gene(s) or body metabolism, changes in the brain structure (called a malformation), lack of oxygen to the brain, brain infections or injury before the seizures begin. Others have had no apparent injury and have been developing normally. There is no evidence that family history, the baby's sex, or factors such as immunizations are related to infantile spasms.

How are Infantile Spasms Diagnosed?

  • A history of what has happened and how symptoms have changed is critical.
  • A physical and neurological exam. 
  • An EEG looks at the electrical activity of the brain. An EEG in a baby with infantile spasms usually shows a pattern called hypsarrhythmia (HIP-sa-RITH-me-ah) when the seizures are not occurring. This high-voltage spike and wave pattern is often helpful in confirming the diagnosis.  
  • Most infants diagnosed with infantile spasms will need other tests like an MRI of the brain, blood and urine tests. 

How is Infantile Spasms treated?

The treatments for children with infantile spasms include:

  • Steroid therapy with adrenocorticotropic hormone (ACTH) by injection into a muscle or prednisone by mouth. 
  • A seizure medication called Sabril® (vigabatrin). 
  • Other anti-seizure medications that may appear helpful for IS include: Depakote® (valproate), Topamax® (topiramate), pyridoxine (vitamin B6), Zonegran® (zonisamide), Onfi® (clobazam) or Klonopin® (clonazepam). Some people like to try one of these before steroid therapy.
  • Somtimes more than one therapy is used at a time - for example, ACTH and Vigabatrin or hydrocortisone and valproate.
  • Sabril® can be especially effective for the short-term treatment of  children with infantile spasms caused by tuberous sclerosis complex (TSC). Tuberous sclerosis is a disorder that can affect the brain, skin, heart, and other parts of the body.
  • Sabril has been associated with damage to the retina of the eye and should be used with caution in children. The retinal damage can result in permanent loss of peripheral vision, but this side effect is of more concern when the drug is used for many months. Monitoring vision in a baby on this drug is important.

Other treatment options:

  • The ketogenic diet has been reported to be safe, well tolerated and possibly effective alternative to treatment in children with infantile spasms who do not respond to standard anti-seizure medications.
  • Epilepsy surgery should be considered in a selected group of patients.  Some children with tuberous sclerosis complex, with malformations of the brain or other may be candidates for surgery if they do not respond to standard anti-seizure medications.

What's the outlook for children with Infantile Spasms?

  • Most children with infantile spasms have intellectual disabilities later in life.
  • Those whose infantile spasms are related to an underlying brain disorder or injury have a higher likelihood of moderate to severe developmental delay.
  • The outlook is brighter for those who were developing normally before the spasms started - 10 to 20% will have normal mental function and some others may be only mildly impaired.
  • Some children with infantile spasms develop autism.
  • Treating seizures eary and appropriately can be very important. 
  • Even if the infantile spasms stop, most children later develop other kinds of epilepsy. About one-fifth of children who have had infantile spasms will evolve into Lennox-Gastaut syndrome.
Authored By: 
Gregory L. Holmes, MD
Robert S. Fisher, MD, PhD
Angel W. Hernandez MD
Authored Date: 
Tuesday, September 3, 2013
Reviewed By: 
Angel W. Hernandez MD | Pediatrics Editor
Reviewed Date: 
Tuesday, December 8, 2015